The present invention relates to an exhaust device of a V-type engine for a vehicle, which is disposed in an engine room of the vehicle.
In a V-type engine for a vehicle, each cylinder bank is arranged in an engine room in the front side of the vehicle. The cylinder bank is directed in a longitudinal direction of the vehicle (a vehicle length direction). An exhaust device of the V-type engine has exhaust manifolds attached to both side portions of the V-type engine in the vehicle width direction, a catalytic converter is attached to a gathering portion of each exhaust manifold in a manner that an axial line of the catalytic converter is extended in a lower direction of the vehicle and one catalytic converter is arranged in a lower portion of an auxiliary machine component in the engine room. In this exhaust device, the catalytic converters are symmetrically arranged in both side portions in the vehicle width direction of the V-type engine in many cases.
In this connection, Patent Document 1 proposes the following constitution. In order to enhance the durability of an air-ratio sensor by decreasing an atmospheric temperature in the periphery of the catalytic converter in the engine room, passage-like duct portions are arranged in both side portions of a heat shielding plate for covering a front face of the catalytic converter.
Patent Document 2 proposes the following constitution. In a transverse V-type engine, a lower end portion of the front side exhaust manifold and a lower end portion of the rear side exhaust manifold are joined to each others so as to compose a single exhaust pipe. In a portion of the exhaust pipe in the front of the engine, a catalytic converter is arranged so that components attached in the periphery of the catalytic converter can be prevented from being thermally deteriorated.    Patent Document 1: Japanese Patent Publication No. 2005-171792A    Patent Document 2: Japanese Patent Publication No. 8-144751A
In the above described related-art V-type engine for a vehicle, the following problems may be encountered. When catalytic converters are symmetrically arranged in both side portions in the vehicle width direction of V-type engine, it is difficult for auxiliary machine components to be arranged in portions except for the upper portions of both the catalytic converters. Accordingly, the auxiliary machine components must be necessarily arranged above both the catalytic converters. In this case, the auxiliary machine components are thermally deteriorated by the heat transmitted from the catalytic converters. Therefore, the durability is lowered.